Third harmonic (THG) microscopy

Nonlinear microscopies have the unique ability to provide micrometer-scale 3D images from within complex, scattering samples like biological tissues.

In particular, third-harmonic generation (THG) microscopy detects interfaces and optical heterogeneities and provides 3D structural images of unstained biological samples. This information can be combined with other nonlinear signals such as 2PEF and SHG.

Since THG is a coherent process, signal generation must be properly analyzed in order to interpret the images. We study the contrast mechanisms in THG microscopy (phase matching, nonlinear susceptibilities), and we develop novel applications such as :
• imaging morphogenesis in small animal models (zebrafish, drosophila);
• imaging lipids in cells and tissues;
• polarization-resolved THG analysis of organized media: human cornea, skin lipids, etc